An open microchannel is defined as a microfluidic channel whose cross-section is composed of solid walls as well as at least one section with open liquid-air interface. Open microchannels present advantageous properties linked to their reliability, function, and manufacturability. Open microchannels solve a problem related to air bubbles, as the gas can escape through the open face of the channel, thus creating a device that is more reliable in comparison to traditional closed channel setups. However, prior to the inventions described herein, flow in open microfluidic channels was not well understood, and the few existing methods demonstrated until now have had limited functionality, namely transporting fluid for a short distance in a straight line, as described in the filed patent Ser. No. 11/470,021 and 09/943,080. A second problem in existing technology relating to open microfluidic channels was the lack of ability to control the flow of fluid, thus preventing the creation of advanced fluid handling platforms designed entirely or in large part based on that technology. Thirdly, there was, prior to the inventions described herein, a lack of tools allowing for the insertion of fluid into, or removal of fluid from, the open channel. All of the known methods relied on dipping a single device into the liquid of interest in order to sample a small amount, rather than having the ability to create networks in which fluid can be inserted at precise locations and at different times. Further, no known method prior to the inventions described herein provides for the removal of fluid from these channels. Thus, there is a need in the art for improved open microfluidic channels and related systems, devices, and methods.